1) What do you mean by health ? (2) What are the needs for individual health ?

'Health' is the state of being well enough to function well physically, mentally and socially.

Good economic conditions and jobs are needed for individual health.

-TheUnknownScientist 72

Health is the condition of being physically, mentally and socially fit not merely the absence of diseases.

The needs for individual health are;

For a healthy life cycle, a person needs to have a balanced diet and has to regularly exercise. One must also live in a proper shelter, take enough sleep and have good hygiene habits.

your answer is rna to the question.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."